I'm an Arab, I get selected in MEL 100% of the time, 100% in BNE and 20% in SYD. You learn to let them do their job because the quicker you comply, and they do the scan, the quicker you are let through. I watch other people argue, yell etc. and I wonder what purpose does it possibly serve.
I do think it ironic that most of the SMP security staff are of Arab background.
I've only had 1 bad incident where a your lad took the wand down the front of my pants. Was thoroughly unimpressed, but he was more embarrassed than I was when I said to him he should really scan other areas.